Adi bin Thabit narrated from his father, from his grandfather (may Allah be pleased with him), that the Prophet (peace and blessings be upon him) said: "The woman with istihadah will leave prayer during the days of her menstruation, then perform ghusl, perform ablution for every prayer, fast and pray."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحيض / 1633